The Lake Heron basin is an intermontane basin located approximately 30 kms west of Mount Hutt. Sediments within the basin are derived from a glacier that passed through the Lake Stream Valley from the upper Rakaia Valley. The lack of major drainage in the south part of the basin has increased the preservation potential of glacial phenomena. The area provides opportunities for detailed glacial geomorphology, sedimentology and micropaleontogical work, from which a very high-resolution study on climate change spanning the Last Glacial Maximum (LGM) through to the present was able to be reconstructed. The geomorphology reveals a complex glacial history spanning multiple glaciations. The Pyramid and Dogs Hill Advance are undated but possibly relate to the Waimaungan and Waimean glaciations. The Emily Formation (EM), previously thought to be MIS 4 (Mabin, 1984), was dated using Be10 to c. 25 ka B.P. The EM was largest advance of the Last Glacial Maximum (LGM). Ice during the LGM was at least 150m thicker than previously thought, as indicated by relatively young ages of high elevation moraines. Numerous moraine ridges and kame terraces show a continuous recession from LGM limits, and, supported by decreasing Be10 ages for other LGM moraines, it seems ice retreat was punctuated by minor glacial readvances and still-stands. These may be associated with decadal-scale climate variations, such as the PDO or early ENSO-like systems. There are relatively little sedimentological exposures in the area other than those on the shores of Lake Heron. The sediment at this location demonstrates the nature of glacial and paraglacial sedimentation during the later stages of ice retreat. They show that ice fronts oscillated across several hundred metres before retreating into Lake Heron proper. Vegetation change at Staces Tarn (1200m asl) indicates climate amelioration in the early Holocene. The late glacial vegetation cover of herb and small shrubs was replaced by a low, montane forest about 7,000 yrs B.P, approximately at the time of the regional thermal maxima. From 7,000 and 1,400 yrs B.P, temperatures slowly declined, and grasses slowly moved back onto the site, although the montane forest was still the dominant vegetation. Fires were frequent in the area extending back at least 6,000 years B.P. The largest fire, about 5,300 yrs B.P, caused major forest disruption. But full recovered occurred within about 500 years. Beech forest appears at the site about 3,300 yrs B.P and becomes the dominant forest cover about 1,400 yrs B.P. Cooler, cloudier winters and disturbance by fire promoted the expansion of beech forest at the expense of the previous low, montane forest. Both the increased frequency of fire events and late Holocene beech spread may be linked to ENSO-related variations in rainfall. The youngest zone is characterised by both a dramatic decline in beech forest and an increase in grasses, possibly representing human activity in the area.

The reliability of foraminifera as stratigraphic index fossils, and as isotopic proxies of marine environments, is based on the assumption that the fossil concepts represent uniform species, responding consistently to their ambient environments. Understanding sources of uncertainty is, therefore, critical. In this dissertation, I explore a potential bias in the application of planktonic foraminifera utilized extensively for Cenozoic paleo-reconstruction and, to a lesser extent, biostratigraphy: the Globigerinoides ruber-elongatus plexus (‘plexus’ meaning a complex network of interconnected members). Taxonomic revisions since 1826 have resulted in the merging of multiple Globigerinoides species names under one general designation (“Globigerinoides ruber”), the implications of which are now under scrutiny. These “morphotypes” of G. ruber have been shown to incorporate stable isotopes and trace elements in seawater dissimilarly, and correspond to multiple genetic species, some of which occupy different environments. Various criteria exist to sub-divide, group, or distinguish members of the Globigerinoides plexus, most notably the recurring use of Globigerinoides elongatus as a less spherical, less symmetrical counterpart to G. ruber. But the efficacy of these various taxonomic criteria has not been tested quantitatively. Most rely on the traits of visually distinctive “end-members,” while specimens in the morphological “transitional zone” are left to an observer’s subjective interpretation. This prevents quantification in census counts, and may lead to erroneous geochemical analyses. Furthermore, molecular clock estimates suggest that the G. elongatus species evolved significantly later than G. ruber, affecting its potential as a biomarker. In this dissertation, I examine the potential of a minimal-criteria system for classifying Globigerinoides-type morphologies using only three conditions: final chamber compression, final chamber asymmetry, and aperture compression. Morphometric analyses on specimens grouped according to this new system allow us to assess to what degree visual classification reflects morphospace discontinuity. Armed with this information, I then explore potential isotopic offsets between members of the Globigerinoides plexus, and its use in reconstructing regional differences in climate or habitat influences in the Gulf of Mexico and Caribbean basins. Finally, having shown that G. ruber and G. elongatus can be reliably visually distinguished, I tracked the species’ fossil presence individually in a deep core from the South China Sea, and confirmed the presence of G. ruber in the South China Sea through the late Miocene, and G. elongatus through the Pleistocene. While it is believed that neither species was traced to its true first occurrence (FO), the relative FO of G. ruber was shown to be 4–5 Ma before G. elongatus

Στην παρούσα εργασία εξετάστηκαν τα πανιδικά σύνολα μικροαπολιθωμάτων με την χρήση 8 δειγμάτων που αποτελούνται από ιζήματα Κάτω πλειστοκαινικής ηλικίας τα οποία συλλέχτηκαν από τμήμα της θέσης 2 της λεκάνης Σουσακίου. Κατά τη μελέτη προσδιοριστήκαν σε επίπεδο είδους, 4 είδη οστρακωδών, 2 είδη τρηματοφόρων και 3 είδη θυσανόποδων, τα οποία χρησιμοποιήθηκαν ως παλαιοοικολογικοι δείκτες για την παλαιοοικολογική και παλαιοπεριβαλλοντική εξέλιξη της ευρύτερης περιοχής του Σουσακίου. / In this study we document microfossil units mostly ostracode assemblages in samples taken from an artificial section of Pleistocene marly sediments, in the tectonically active Sousaki basin in Southern Greece,to enhance palaeoenvironmental reconstructions.

Στην παρούσα εργασία εξετάστηκαν τα πανιδικά σύνολα μικροαπολιθωμάτων με την χρήση 9 δειγμάτων που πάρθηκαν από ιζήματα Πλειστοκαινικής ηλικίας, και συλλέχθηκαν σε μία τομή που βρίσκεται ΒΔ των Αγίων Θεοδώρων και ανήκει στην ευρύτερη λεκάνη Σουσακίου. Κατά τη μελέτη προσδιορίστηκαν σε επίπεδο είδους όπου αυτό ήταν εφικτό, οστρακώδη, τρηματοφόρα, γαστερόποδα και δίθυρα. Τα δεδομένα αυτά χρησιμοποιήθηκαν ως δείκτες για την παλαιοοικολογική και παλαιοπεριβαλλοντική εξέλιξη μέρους της λεκάνης Σουσακίου. Προέκυψε ότι η ιζηματογένεση πραγματοποιήθηκε σε δύο λεκάνες ιζηματογένεσης, μια ρηχής θαλάσσιας προέλευσης και μια λιμνοθαλάσσιας . Οι δύο αυτές ακολουθίας ήρθαν σε επαφή μέσω της τεκτονικής. / In this project, the microfossil fauna of 9 samples were studied. The sedimentary sequence is of Pleistocene age and the samples were selected within a stratigraphic sequence located NW of Ag. Theodoroi village. These sediments are part of the sedimentary sequence of Sousaki basin. Ostracodes, Foraminifera , Gastropods and Bivalves were udentified. These data were used to reconstruct the palaeoecological and palaeoenvironmental evolution of part of the Sousaki basin. The sediments were deposited in two basins, one marine and one lagoonal. These two basins are in contact through tectonics.

The Lake Heron basin is an intermontane basin located approximately 30 kms west of Mount Hutt. Sediments within the basin are derived from a glacier that passed through the Lake Stream Valley from the upper Rakaia Valley. The lack of major drainage in the south part of the basin has increased the preservation potential of glacial phenomena. The area provides opportunities for detailed glacial geomorphology, sedimentology and micropaleontogical work, from which a very high-resolution study on climate change spanning the Last Glacial Maximum (LGM) through to the present was able to be reconstructed. The geomorphology reveals a complex glacial history spanning multiple glaciations. The Pyramid and Dogs Hill Advance are undated but possibly relate to the Waimaungan and Waimean glaciations. The Emily Formation (EM), previously thought to be MIS 4 (Mabin, 1984), was dated using Be10 to c. 25 ka B.P. The EM was largest advance of the Last Glacial Maximum (LGM). Ice during the LGM was at least 150m thicker than previously thought, as indicated by relatively young ages of high elevation moraines. Numerous moraine ridges and kame terraces show a continuous recession from LGM limits, and, supported by decreasing Be10 ages for other LGM moraines, it seems ice retreat was punctuated by minor glacial readvances and still-stands. These may be associated with decadal-scale climate variations, such as the PDO or early ENSO-like systems. There are relatively little sedimentological exposures in the area other than those on the shores of Lake Heron. The sediment at this location demonstrates the nature of glacial and paraglacial sedimentation during the later stages of ice retreat. They show that ice fronts oscillated across several hundred metres before retreating into Lake Heron proper. Vegetation change at Staces Tarn (1200m asl) indicates climate amelioration in the early Holocene. The late glacial vegetation cover of herb and small shrubs was replaced by a low, montane forest about 7,000 yrs B.P, approximately at the time of the regional thermal maxima. From 7,000 and 1,400 yrs B.P, temperatures slowly declined, and grasses slowly moved back onto the site, although the montane forest was still the dominant vegetation. Fires were frequent in the area extending back at least 6,000 years B.P. The largest fire, about 5,300 yrs B.P, caused major forest disruption. But full recovered occurred within about 500 years. Beech forest appears at the site about 3,300 yrs B.P and becomes the dominant forest cover about 1,400 yrs B.P. Cooler, cloudier winters and disturbance by fire promoted the expansion of beech forest at the expense of the previous low, montane forest. Both the increased frequency of fire events and late Holocene beech spread may be linked to ENSO-related variations in rainfall. The youngest zone is characterised by both a dramatic decline in beech forest and an increase in grasses, possibly representing human activity in the area.

Thesis (Ph. D.)--Florida State University, 2004. / Advisor: Dr. Anthony J. Arnold, Florida State University, College of Arts and Sciences, Dept. of Geological Sciences. Title and description from dissertation home page (viewed Aug. 27, 2004). Includes bibliographical references.

Ο σκοπός της εργασίας αυτής είναι η μελέτη και η παρατήρηση των συνθηκών στην περιοχή του Αμβρακικού κόλπου μέσω της μελέτης των τρηματοφόρων που βρέθηκαν ύστερα από συστηματική πυρηνοληψία στην περιοχή. / The purpose of this paper is the study and observation of conditions in the Amvrakikos bay through the study of foraminifera found after systematic coring in the area.

No description available.

A unique assemblage of in situ microstromatolites, articulated intraclastic microstromatolites, and disarticulated stromatolites has been identified from drill cores of the 2.3 G.a. Transvaal Sequence, South Africa. These structures occur in organic-rich lenticular and nodular replacement black cherts which are associated with early diagenetic dolomite. Petrographic evidence indicates that the chert has formed via a primary carbonate and organic matrix--partial dolomitization--silicification paragenetic sequence; and that dolomitization and silicification were closely contemporaneous diagenetic events. Microstructures which resemble three dimensionally preserved microfossils are found in the majority of the silicified Transvaal cores. These fossil-like microstructures can be grouped broadly into three morphological types: (1) filaments, (2) ovoid or spheroidal forms, and (3) bacteria-like microstructures. Certain of the filamentous forms which are associated with pyrite mineral grains are clearly of abiological origin, and their formation can be explained in the context of sedimentary diagenesis and mineral paragenesis. The three dimensional association of the ovoid and bacteria-like microstructures to the microstromatolites is such as would be predicted from studies of modern cyanobacterial/microbial mat ecosystems. Hence, these microstructures are considered to be potential microfossils. The Transvaal microstromatolitic materials represent some of the smallest stromatolites yet described from either Proterozoic or Phanerozoic sedimentary rocks. Nearly all of the basic stromatolite growth forms (i.e. columnar, bulbous, nodular, and stratiform) are represented in the Transvaal assemblage. Thus, stromatolite diversity at the "basic growth form" level apparently did not evolve through geologic time. Physical and chemical environmental parameters probably controlled stromatolite morphogenesis only to the extent that they influenced the steady state balance of microstromatolite microbial communities. Indirect evidence suggests that the Transvaal microstromatolites grew via the precipitation of primary carbonate at some level within the structures and that a correlation exists between the degradation of primary producer organic carbon and the precipitation of a structurally supportive carbonate mineral matrix.

In this study diatom distribution within the lower Save River, Mozambique, has been identified from surface sediments, surface water, mangrove cortex and buried sediments. Sandy units, bracketing a geographically extensive clay layer, have been dated with optical stimulated luminescence (OSL). Diatom analysis has been used to interpret the spatial salinity gradient and to discuss taphonomic processes within the delta. Previously, one study has been performed in the investigated area and it is of great importance to continue to identify diatom distributions since siliceous microfossils are widely used for paleoenvironmental research. Two diatom taxa, which were not possible to classify to species level have been identified; Cyclotella sp. and Diploneis sp. It is suggested that these represent species not earlier described; however they are assigned a brackish water affinity. Diatom analysis from surface water, surface sediments and mangrove cortex indicate a transition from ocean water to a dominance of freshwater taxa c. 10 km upstream the delta front. Further, ratios between marine/brackish taxa for samples from surface water and surface sediments do not correspond. It is therefore suggested that diatoms in surface sediments underestimate prevailing salinity conditions in water. In the investigated area extensive taphonomic processes seem to have large impact on diatom frustules in sediments and may bias interpretations. Therefore it is recommended to carefully investigate geology, geomorphology and vegetation before diatom analysis is applied in studies of delta paleoenvironments.